Vodyanoi originally inhabited the rivers and lakes of Eastern Europe, but over the years, these malignant spirits followed the currents west, flowing along rivers and streams to torment different cultures.

The vodyanoi are described by the few survivors who encountered them as a cross between a nightmarish fish of terrible size and a bloated frog with rows of razor sharp teeth. They generally lurk within a body of water until a victim comes too close to the shore. Then, with a powerful thrust from their large tail, the vodyanoi can leap out of the water, and use their lateral fins to propel them through the air and onto their target. Victims are usually devoured on the shore or dragged to a watery death.